二路归并排序

 
void mergeSort(int data[],int temp[],int a,int b)
{
if(a<b)
{
int mid=(a+b)/2;
mergeSort(data,temp,a,mid);
mergeSort(data,temp,mid+1,b);
merge(data,temp,a,mid,b);
}
}
void merge(int data[],int temp[],int low,int mid,int high)
{
int i=low,j=mid+1,k=low;
while(i<=mid&&j<=high){
if(data[i]<=data[j]) // 小于表示从小到大排序
    temp[k++]=data[i++];
else
    temp[k++]=data[j++];
}
while(i<=mid)
    temp[k++]=data[i++];
while(j<=high)
    temp[k++]=data[j++];
for(i=low;i<=high;i++)// 写回原数组
    data[i]=temp[i];
}